Sound transmitter



June 2, 1925.-

SOUND TRANSMITTE R File d June 22, 1923 Patented June 2, 1925.

mmmx A. warxms, or CHICAGO, rumors.

I v 1,540,506 PATENT OFFICE-"7..

' scum) TRANSMITTER.

Application flled June 22, 1923. Serial No. 647,005

To all it may concern.-

Be itknown that I, FREDERICK A. WAT- KINs, a citizen of-the United States, and a resident'of Chicago, inthe county'of Cook and State of Illinois, have invented certain new a and useful Improvements in Sound Transmitters; and 'I do'her'eby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the characters of reference markedthereon, which form a part'of this specification. v This invention relates to improvementsin sound transmitters adapted for use with telephone transmitters and like instruments of that kind including within the mouthpiece ofthetransmitten a-nd infront of a diaphragm constituting part of thetransmitter, a receptacle to confine'a. bodyof air which lies against the'diaphragm, the said receptacle serving, in addition'to its function of confining the body of air, as a means to deflect'against the diaphragm sound waves which would otherwise be dissipated outwardly and result "in apartial loss of powerto vibrate the diaphragm. There- .sult is that the diaphragm can bev efliciently vibrated by'small vibrations produced by low or so-called whispering tones.

Among the objects'of the invention are to improve the transmitting effects ofsuchan imprisoned body of air and the reflecting effects of the receptacle .whichret'ains the body of air, so as to produce, with greater sharpness, the tone effects of'low vibrations at a receiving instrument "constructed to transmute vibrations intosound waves.

' Other objects of the invention are to otherwise improve, simplify and reduce the cost of the construction of such a device, and the invention consists in the elements'and combination of elements shown in the drawings and described in the 'specification, and is pointed out in the appended claims. 7

In thedrawingSr Figure 1 is a side elevation'of a trans-' mitter embodying my invention;

Figure 2*is an axial section thereof.

Figure 3 is a front'view of the ringmember clasp and receptacle withlthe mouthpiece omitted. i

Figure 4 is aside elevation of the air body.

confining receptacle and the means for holding'it'in'place. s. I I

' Figure 5 is a side elevation of-the airbody confining "receptacle and sound wave refiector. a The invention will be described in connection with a known telephone transmitter for the purpose of readily understanding the purpose and function thereof, but said invention may be embodied in transmitters for other uses.

The bell-shaped mouthpiece 10, which can be made of glass or other 'suitable material, is exteriorly formed at its rear, smaller end with an'annular rib 11 that surrounds the open rear end of the mouthpiece.Said flanged end of the mouthpiece fits with a snap" action into a clasp designated as a whole by 12. The said clasp is of ring-like formation and is'preferably made of resilient sheet metal. It is slitted to produce clasp fingers 13 which are shaped at their outer ends to readily receive the flange 11 to permit it to be snapped into and removed from the clasp.

J14 designates a ring member which is formed with a rearwardly extending tubular, exteriorly threaded portion 15 to fit within a' threaded'opening of the wall of a box orchamber which, in practice, supports the diaphragm 16. Said ring member 14 has a .radial'flange' 17 to which the clasp member 12 is fitted and attached. As herein shown, the flange 17 is provided radially within: its margin on its outer face. with a recessed seat 18 tojreceive an annular inturned flange 19 ofthe clasp 12 which lies flatagainst said seat, withits internal edge abutting an annular shoulder between said seat and the deeper front face 18 of said ringmember. Said clasp isfastened to said ring member by radially expanding the portion 18 of the ring member that lies between the bore of the ring member and said recess.

The'said ring member may be expanded-by a tool having radial ribs to produce the radia-l indentation 17 shown in Figure 3.

Said tool is thrust axially against thering member, and confines the metal thereof flOIlI- endwise displacement and thereby expands the metal of the ring member both inwardly and outwardly against the inner edge of the flange 19 and towards the receptacle 20 to cause the metal of the ring member to tend to 'flow over said edge and against the base of said receptacle to hold said parts in place. p

'20 designates a receptacle which is 10- cated axially in said mouthpiece and the mounting ring let. It is made of sheet metal by suitable swaging operation, and is closed and internally conoidal at'its outer end and externally cylindric at its inner end. The external diameter ofthe rearmost cylindric portion 21 of said receptacle is such as to be pressed with a close fit into the'bore of the mounting ring ll and is held "therein by such lit. The exterior diameter of said re ceiiita-cle is slightly less than the interior diameter of the smaller, rear part of the mouthpiece 10 so as to provide an annular passage 22 for sound waves coming from the forward larger end the mouthpiece. The receptacle provided near its base portion with a plurality of openings 23 which communicate with the annular .pas sage 22 to carry the sound waves backwardly through the rear hollow base of said rcceptacle to the diaphragm 16.

The said receptacle 20 is formed to pro due-e an internal cono idal .faee 24 at its forward end and is closed from its extreme forward end back to the margins 25 of the openings 23 so as to form a chamber. 26 within which, and between the bounding walls of the chamber and the diaphragm, a body of air is confined.

In accordance with one phase-of the inention. the length of said receptacle 20 from the outer margins 25 of the openings 23 to the inner conoidal face of the outer end of the receptacle is not less than the internal diameter of the casing :at said openings 23 and at the base 21 of the recep: tacle. I tind in practice that superior results are obtained by making the axial dimension referred to about twenty-five per cent greater than the said internal diametric dii'nension. This appears to be due to the fact that the pressure undulations :of a confined air body of I comparatively long length, relatively to its diameter. produced by sound waves projected throu'gththe flaring mouthpiece. around and through i the receptacle to the diaphragm, and the rebounding effect of the sound W Yes, due to the conoidal ended portion of the receptacle, has the ett'ect of increasing the pressure of the confined air body beyond normal, under the control of direct and rebounding somid waves. and that said pressure acts against said diaphragm with increased force to produce good sound wave definition char acteristics. a

From what has been said in connection with the "drawings, it will be clear that the construction of the transmitter, both with respect to the manufacture of its elements and the assemblage thereof. is economical and the resultant device isv simple and sturdy. i t

The part 21 of said receptacle constitutes a lubular anchor which can forced into the ring 1 L either before or after the ring is assembled with the mouthpiece and its clasp, it being practical and preferable to insert said receptacle in place through the rear endof said ring member.

I claim as my invention:

1. A sound transmitter comprising a mouthpiece having a smaller end, and means within said mouthpiece and anchored within its smaller end to confine a body of air in front of the diaphragm of a length greater than the diameter of said body, the anchor comprising a tubular extension to constitute an enclosed sound passage Ind closely fitting within the smaller end of the mouth piece, the sound passage internally communicating with said mouthpiece and with the interior of said air confining means.

2. A sound transmitter comprising a flaring mouthpiece adapted at its smaller open end to face a diaphragm and means insertable within said smaller end to confine a body of air a distance in front of the diaphragm and of an air confining length substa-ntially great-er than the diameter of said body.

3. A sound transmitter comprising a flaring mouthpiece adapted at its smaller end to face a diaphragm and an air confining receptacle Within the smaller end of said mouthpiece having arearward-ly extended tubular anchor extension constituting a sound passage arranged to produce therearound a continuous annular sound wave passage, said receptacle having an running in its circumferential wall abreast and eommun-icating with said sound passage.

4. A sound transmitter comprising a flaring mouthpiece adapted at its smaller end to :face a diaphragm and an air confining receptacle within the smaller end of said mouthpiece arranged to produce therea-mmul an annular sound wave passage, said recepta-cle having an opening in its circumferential wall abreast said sound usage and extend-ing rearwazrdly from said o uin-ing to constitute a hollow cylindric anchor extension.

5. A sound transmitter cmnprising a flaring mouthpiece adapted at its smaller and to face a diaphragm and a combined sound reflector and air body ietainer within said mouthpiece open at its rear end and closed at its front. end, and provided with a solid tubular anchor extension constituting an enclose-d sound passage arranged to form a continuous annular sound wave passage be tween it and said mouthpiece, and provided in front. of said extension with a cinnamferentia'l opening communicating with said passage.

"6. A sound transmitter comprising a flaring mouthpiece adapted at its smaller and to face a diaphragm and a CORlllifldSOU-Dl] reflector and air body retainer within said length of said receptacle from the outer end thereof to said circumferential openings being not less than the internal diameter of said receptacle.

7. A soundtransmitter comprising a flaring mouthpiece, a ring base on which the smaller end of the mouthpiece is mounted, and an elongated tubular air body retaining and reflector shell open at its rear end and closed at its frontend and extending into and enclosed by said ring base.

8. A sound transmittercomprising a flaring mouthpiece, a ring base on which the smaller end of the mouthpiece is mounted,

and an elongated tubular air body retaining and reflector shell open at its'rear end and closed at its front end and extending into and enclosed in said ring base and forming between it and the smaller end of the mouthpiece a sound wave passage and passage with circumferential 9. A soundtransmitter comprising a ring base provided with a mouthpiece mounting and a receptacle open at its rear end and closed at its front end and having a close fitconnection to said ring base.

10. A sound transmitter comprising a ring base and provided with a mouthpiece mounting and a receptacle open at its rear end and closed at'its front end and having a close fit connection to said ring base, said receptacle being provided in front of said ring base with a circun'iferential opening.

11. A sound transmitter comprising a ring base and provided with a mouthpiece mounting and a receptacle open at its rear end and closed at its front end and having a close fit connection to said ring base. said receptacle being provided in front of said ring base with a circumferential opening, the internal diameter of said receptacle at said circumferential opening being less than the axial dimension thereof from said circumferential opening outwardly to the closed end of said receptacle.

12. In a sound transmitter a combined air body retainer and sound Wave reflector receptacle, said receptacle having a cylindric anchor part at its rear end and closed at its forward end and provided in its wall between its ends with a radial opening extending through the wall from the inner to the outer part of said retainer.

13. In a sound transn'iitter a combined air body retainer and sound wave reflector receptacle, said receptacle being formed at its rear end with a cylindric anchor end and closed at its forward end and provided between its ends with a radial opening extending radially through said retainer, the length of said reflector from its closed end to said radial opening being greater than the internal diameter of said receptacle.

1 14. A sound transmitter comprising aring base formed at its forward side with a mouth piece clasp and a sound wave confining and reflecting receptacle formed at its rear end to constitute an anchoring extension telescopic in the ring base in rear of said mouthpiece mounting.

15. A sound transmitter having an axial bore and forward thereof a mouthpiece mounting and a hollow sound wave confining and reflecting receptacle having a cylindric open base fixed insaid bore and having forwardly therefrom a closed internally conoidal reflecting face.

16. A sound transmitter having an axial bore and forward thereof a mouthpiece mounting and a hollow sound wave confining and reflecting receptacle formed with a cylindric open base having a close fit in said bore and extending forwardly therefrom and formed with a closed end, and a mouthpiece fixed to said clasp and enclosing said receptacle, between which and said receptacle a sound wave passage is formed that communicates with the rear hollow end of said receptacle.

In witness whereof I claim the foregoing as my invention, I hereunto append my signature this 11th day of June, 1923. j

FREDERICK A. IVATKINS. 

